. (a) It improves efficiency by reducing the losses known as " I ² R Loss" (or "Copper Loss"): . Efficiency is defined as (output power / input power) x 100% . = Output Power x 100 % ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾ Output Power + Losses . Output Power is equal to Output Voltage x Output Current, and any given output power can either be supplied at a low voltage with high current or high voltage with low current. . If the distribution voltage is doubled, the distribution current is halved, and the I ² R losses (which are proportional to the square of the current) drop to one quarter with a consequent improvement in efficiency. . (b) A higher distribution voltage is more dangerous, and thus deters would be metal thieves from attempting to steal the cables in order to weight them in for scrap.
Best wishes - Majikthise. .
High voltage greatly lowers the current transmission to reduce energy loss.